1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to improving communication performance.
2. Introduction
Wireless communication systems are widely deployed to provide various types of communication (e.g., voice, data, multimedia services, etc.) to multiple users. As the demand for high-rate and multimedia data services rapidly grows, there lies a challenge to implement efficient and robust communication systems with enhanced performance.
To supplement the base stations of a conventional mobile phone network (e.g., a macro cellular network), small-coverage base stations may be deployed, for example, in a user's home. Such small-coverage base stations are generally known as access point base stations, home NodeBs, or femto cells and may be used to provide more robust indoor wireless coverage to mobile units. Typically, such small-coverage base stations are connected to the Internet and the mobile operator's network via a DSL router or a cable modem.
In a typical macro cellular deployment the RF coverage is planned and managed by cellular network operators to optimize coverage. Femto base stations, on the other hand, may be installed by the subscriber personally and deployed in an ad-hoc manner. Consequently, femto cells may cause interference both on the uplink (“UL”) and downlink (“DL”) of the macro cells. For example, a femto base station installed near a window of a residence may cause significant downlink interference to any access terminals outside the house that are not served by the femto cell. Also, on the uplink, home access terminals that are served by a femto cell may cause interference at a macro cell base station (e.g., macro NodeB).
Interference between the macro and femto deployments may be mitigated by operating the femto network on a separate RF carrier frequency than the macro cellular network.
Femto cells also may interfere with one another as a result of unplanned deployment. For example, in a multi-resident apartment, a femto base station installed near a wall separating two residences may cause significant interference to a neighboring residence. Here, the strongest femto base station seen by a home access terminal (e.g., strongest in terms of RF signal strength received at the access terminal) may not necessarily be the serving base station for the access terminal due to a restricted association policy enforced by that femto base station.
RF interference issues may thus arise in a communication system where radio frequency (“RF”) coverage of femto base stations is not optimized by the mobile operator and where deployment of such base stations is ad-hoc. Thus, there is a need for improved interference management for wireless networks.